Shown in FIG. 1 is a somewhat schematic layout of a conventional barn floor 10 having two primary gutters 12a and 12b that run most of the length of the floor, but only a small portion of the width of the floor, draining into a secondary gutter 13. The gutters 12a and 12b are separated by a raised center floor portion 14. Generally, livestock will be positioned on the raised center floor portion 14 in two rows, facing each other, with the primary gutters 12a and 12b positioned along the rear of the animals so as to collect the manure and other waste materials from the animals. According to conventional methods for cleaning the gutters, respective scrapers 16a and 16b are positioned in gutters 12a and 12b. The two scrapers 16a and 16b are connected to a single endless chain 18. Beginning with the first scraper 16a, the path of the chain 18 leads lengthwise within the gutter 12a to a first distal wheel 20, at the distal end of the gutter 12a, then proceeds across to a second distal wheel 22 in the opposite gutter 12b, then lengthwise within the gutter 12b to the second scraper 16b, then continuing lengthwise to a first proximal wheel 24 at the proximal end of the barn floor 10, then through a drive tower 26 (to be explained in more detail below), then to a second proximal wheel 28 in line with the first gutter 12a, where the chain continues within the gutter 12a and connects with the first scraper 16a. The drive tower 26 drives the chain 18 so as to move the scrapers 16a and 16b within the gutters 12a and 12b. The scrapers 16a and 16b are collapsible so that they collapse when moving away from the secondary gutter 13, and expand when moving toward the secondary gutter, so as to move any manure in the primary gutters into the secondary gutter, for final disposal or removal from the barn. Drive tower 26 may be controlled by a controller located nearby, such as control box 30 on a nearby wall in the barn.
FIG. 2 is an enlarged elevational view of drive tower 26. As can be seen there, a conventional drive tower 26 may have a pair of feed wheels 32a and 32b journaled thereto, one at each side of the tower, each of which admits the chain from its respective side. As the chain 18 enters the tower from one side, the chain moves up the tower 26 and passes over a pocket sprocket or drive sprocket 34. The drive sprocket 34 is driven by a gearbox 36, connected to the drive sprocket by a rotor shaft 38. Gearbox 36 is in turn driven by a motor 37 by way of a pulley and belt system, reducer, or other suitable transmission system.
While this arrangement works well in smaller barns, where the total chain length is 1000 feet or less, problems arise when the chain length exceeds 1000 feet, and in some barns, the desired chain length can extend up to 5000 feet or more. In such long chain situations, even though the chain is tensioned at installation by various adjustments made to the drive tower 26, the chain can have slack in it, to an extent even more than the chain tensioning built into the drive tower can absorb, based on various factors, including general chain wear, the possibility of chain stretching due the forces at work, and general chain slack that cannot be completely eliminated with the primary chain tensioning provided by the drive tower. That excess chain can build up in the area 39 near the feed wheels 32a, 32b. Primary chain tension is generally applied at the drive tower, but the effect of that preload on the chain 18 generally increases the load on the chain and hence the stresses within the chain, in turn causing increased wear. The preloaded tension at the drive tower has to be so great, to avoid the chance of jamming in long chain systems, that the chain is very tight even without moving under load. Without that high level of tension, depending on the direction of rotation of the drive sprocket, the feed wheel 32a, 32b towards which the drive sprocket is rotating can experience jamming. The chain 18 builds up at the bottom of drive tower 26, again in areas 39, due to lack of chain movement.
This invention relates to improvements over the structures described above, and to solutions to problems raised or not solved thereby.